a5094f7d7f
- if an exception occurs in kernel and this exception is not handled in an sane way and the kernel crashes, it also dumps what was loaded in the general purpose registers exactly at the time of the exception to help to debug the problem
282 lines
8 KiB
C
282 lines
8 KiB
C
/* This file contains a simple exception handler. Exceptions in user
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* processes are converted to signals. Exceptions in a kernel task cause
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* a panic.
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*/
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#include "../../kernel.h"
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#include "proto.h"
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#include <signal.h>
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#include <string.h>
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#include <assert.h>
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#include "../../proc.h"
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#include "../../proto.h"
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extern int vm_copy_in_progress, catch_pagefaults;
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extern struct proc *vm_copy_from, *vm_copy_to;
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void pagefault( struct proc *pr,
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struct exception_frame * frame,
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int is_nested)
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{
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int in_physcopy = 0;
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reg_t pagefaultcr2;
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assert(frame);
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pagefaultcr2 = read_cr2();
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#if 0
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printf("kernel: pagefault in pr %d, addr 0x%lx, his cr3 0x%lx, actual cr3 0x%lx\n",
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pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
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#endif
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if(pr->p_seg.p_cr3) {
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assert(pr->p_seg.p_cr3 == read_cr3());
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}
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in_physcopy = (frame->eip > (vir_bytes) phys_copy) &&
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(frame->eip < (vir_bytes) phys_copy_fault);
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if((is_nested || iskernelp(pr)) &&
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catch_pagefaults && in_physcopy) {
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#if 0
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printf("pf caught! addr 0x%lx\n", pagefaultcr2);
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#endif
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if (is_nested) {
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frame->eip = (reg_t) phys_copy_fault_in_kernel;
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}
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else {
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pr->p_reg.pc = (reg_t) phys_copy_fault;
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pr->p_reg.retreg = pagefaultcr2;
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}
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return;
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}
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/* System processes that don't have their own page table can't
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* have page faults. VM does have its own page table but also
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* can't have page faults (because VM has to handle them).
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*/
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if(is_nested || (pr->p_endpoint <= INIT_PROC_NR &&
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!(pr->p_misc_flags & MF_FULLVM)) || pr->p_endpoint == VM_PROC_NR) {
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/* Page fault we can't / don't want to
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* handle.
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*/
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printf("pagefault for process %d ('%s'), pc = 0x%x, addr = 0x%x, flags = 0x%x, is_nested %d\n",
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pr->p_endpoint, pr->p_name, pr->p_reg.pc,
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pagefaultcr2, frame->errcode, is_nested);
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proc_stacktrace(pr);
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if(pr->p_endpoint != SYSTEM) {
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proc_stacktrace(proc_addr(SYSTEM));
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}
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printf("pc of pagefault: 0x%lx\n", frame->eip);
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panic("page fault in system process: %d", pr->p_endpoint);
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return;
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}
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/* Don't schedule this process until pagefault is handled. */
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assert(pr->p_seg.p_cr3 == read_cr3());
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assert(!RTS_ISSET(pr, RTS_PAGEFAULT));
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RTS_SET(pr, RTS_PAGEFAULT);
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/* Save pagefault details, suspend process,
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* add process to pagefault chain,
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* and tell VM there is a pagefault to be
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* handled.
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*/
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pr->p_pagefault.pf_virtual = pagefaultcr2;
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pr->p_pagefault.pf_flags = frame->errcode;
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pr->p_nextpagefault = pagefaults;
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pagefaults = pr;
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send_sig(VM_PROC_NR, SIGKPF);
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return;
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}
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/*===========================================================================*
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* exception *
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*===========================================================================*/
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PUBLIC void exception_handler(int is_nested, struct exception_frame * frame)
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{
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/* An exception or unexpected interrupt has occurred. */
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struct ex_s {
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char *msg;
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int signum;
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int minprocessor;
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};
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static struct ex_s ex_data[] = {
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{ "Divide error", SIGFPE, 86 },
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{ "Debug exception", SIGTRAP, 86 },
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{ "Nonmaskable interrupt", SIGBUS, 86 },
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{ "Breakpoint", SIGEMT, 86 },
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{ "Overflow", SIGFPE, 86 },
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{ "Bounds check", SIGFPE, 186 },
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{ "Invalid opcode", SIGILL, 186 },
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{ "Coprocessor not available", SIGFPE, 186 },
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{ "Double fault", SIGBUS, 286 },
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{ "Coprocessor segment overrun", SIGSEGV, 286 },
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{ "Invalid TSS", SIGSEGV, 286 },
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{ "Segment not present", SIGSEGV, 286 },
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{ "Stack exception", SIGSEGV, 286 }, /* STACK_FAULT already used */
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{ "General protection", SIGSEGV, 286 },
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{ "Page fault", SIGSEGV, 386 }, /* not close */
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{ NIL_PTR, SIGILL, 0 }, /* probably software trap */
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{ "Coprocessor error", SIGFPE, 386 },
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{ "Alignment check", SIGBUS, 386 },
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{ "Machine check", SIGBUS, 386 },
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{ "SIMD exception", SIGFPE, 386 },
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};
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register struct ex_s *ep;
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struct proc *saved_proc;
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/* Save proc_ptr, because it may be changed by debug statements. */
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saved_proc = proc_ptr;
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ep = &ex_data[frame->vector];
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if (frame->vector == 2) { /* spurious NMI on some machines */
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printf("got spurious NMI\n");
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return;
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}
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/*
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* handle special cases for nested problems as they might be tricky or filter
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* them out quickly if the traps are not nested
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*/
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if (is_nested) {
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/*
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* if a problem occured while copying a message from userspace because
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* of a wrong pointer supplied by userland, handle it the only way we
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* can handle it ...
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*/
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if (((void*)frame->eip >= (void*)copy_msg_to_user &&
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(void*)frame->eip <= (void*)__copy_msg_to_user_end) ||
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((void*)frame->eip >= (void*)copy_msg_from_user &&
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(void*)frame->eip <= (void*)__copy_msg_from_user_end)) {
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switch(frame->vector) {
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/* these error are expected */
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case PAGE_FAULT_VECTOR:
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case PROTECTION_VECTOR:
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frame->eip = (reg_t) __user_copy_msg_pointer_failure;
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return;
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default:
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panic("Copy involving a user pointer failed unexpectedly!");
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}
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}
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}
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if(frame->vector == PAGE_FAULT_VECTOR) {
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pagefault(saved_proc, frame, is_nested);
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return;
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}
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/* If an exception occurs while running a process, the is_nested variable
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* will be zero. Exceptions in interrupt handlers or system traps will make
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* is_nested non-zero.
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*/
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if (is_nested == 0 && ! iskernelp(saved_proc)) {
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#if 0
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{
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printf(
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"vec_nr= %d, trap_errno= 0x%lx, eip= 0x%lx, cs= 0x%x, eflags= 0x%lx\n",
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frame->vector, (unsigned long)frame->errcode,
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(unsigned long)frame->eip, frame->cs,
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(unsigned long)frame->eflags);
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printseg("cs: ", 1, saved_proc, frame->cs);
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printseg("ds: ", 0, saved_proc, saved_proc->p_reg.ds);
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if(saved_proc->p_reg.ds != saved_proc->p_reg.ss) {
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printseg("ss: ", 0, saved_proc, saved_proc->p_reg.ss);
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}
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proc_stacktrace(saved_proc);
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}
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#endif
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cause_sig(proc_nr(saved_proc), ep->signum);
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return;
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}
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/* Exception in system code. This is not supposed to happen. */
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if (ep->msg == NIL_PTR || machine.processor < ep->minprocessor)
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printf("\nIntel-reserved exception %d\n", frame->vector);
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else
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printf("\n%s\n", ep->msg);
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printf("is_nested = %d ", is_nested);
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printf("vec_nr= %d, trap_errno= 0x%x, eip= 0x%x, "
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"cs= 0x%x, eflags= 0x%x trap_esp 0x%08x\n",
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frame->vector, frame->errcode, frame->eip,
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frame->cs, frame->eflags, frame);
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printf("KERNEL registers :\n");
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printf(
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"\t%%eax 0x%08x %%ebx 0x%08x %%ecx 0x%08x %%edx 0x%08x\n"
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"\t%%esp 0x%08x %%ebp 0x%08x %%esi 0x%08x %%edi 0x%08x\n",
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((u32_t *)frame)[-1],
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((u32_t *)frame)[-2],
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((u32_t *)frame)[-3],
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((u32_t *)frame)[-4],
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((u32_t *)frame)[-5],
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((u32_t *)frame)[-6],
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((u32_t *)frame)[-7],
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((u32_t *)frame)[-8]
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);
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printseg("ker cs: ", 1, NULL, frame->cs);
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printseg("ker ds: ", 0, NULL, DS_SELECTOR);
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/* TODO should we enable this only when compiled for some debug mode? */
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if (saved_proc) {
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printf("scheduled was: process %d (%s), ", proc_nr(saved_proc), saved_proc->p_name);
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printf("pc = %u:0x%x\n", (unsigned) saved_proc->p_reg.cs,
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(unsigned) saved_proc->p_reg.pc);
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proc_stacktrace(saved_proc);
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panic("exception in a kernel task: %d", saved_proc->p_endpoint);
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}
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else {
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/* in an early stage of boot process we don't have processes yet */
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panic("exception in kernel while booting");
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}
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}
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/*===========================================================================*
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* stacktrace *
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*===========================================================================*/
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PUBLIC void proc_stacktrace(struct proc *whichproc)
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{
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reg_t v_bp, v_pc, v_hbp;
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int iskernel;
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v_bp = whichproc->p_reg.fp;
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iskernel = iskernelp(whichproc);
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printf("%-8.8s %6d 0x%lx ",
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whichproc->p_name, whichproc->p_endpoint, whichproc->p_reg.pc);
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while(v_bp) {
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#define PRCOPY(pr, pv, v, n) \
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(iskernel ? (memcpy((char *) v, (char *) pv, n), OK) : \
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data_copy(pr->p_endpoint, pv, KERNEL, (vir_bytes) (v), n))
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if(PRCOPY(whichproc, v_bp, &v_hbp, sizeof(v_hbp)) != OK) {
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printf("(v_bp 0x%lx ?)", v_bp);
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break;
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}
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if(PRCOPY(whichproc, v_bp + sizeof(v_pc), &v_pc, sizeof(v_pc)) != OK) {
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printf("(v_pc 0x%lx ?)", v_bp + sizeof(v_pc));
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break;
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}
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printf("0x%lx ", (unsigned long) v_pc);
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if(v_hbp != 0 && v_hbp <= v_bp) {
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printf("(hbp %lx ?)", v_hbp);
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break;
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}
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v_bp = v_hbp;
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}
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printf("\n");
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}
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